Looking to buy a gift certificate for my daughter, who recently moved to Austin, and her yard is pretty bare.
Can anyone recommend a nice nursery with a big selection of healthy plants and accessories?

It's been a while since i lived in Austin, and none come immediately to mind. But you might contact the Lady Bird Johnson Wildflower Center and the Zilker Botanical Garden to see what they suggest.

http://www.wildflower.org
http://www.zilkergarden.org

Also, where in Austin does your daughter live, and what in particular does she need (trees, shrubs, bedding plants, flowers, etc.)? That might influence suggestions (and you might not want to give her a gift certificate to a far north nursery if she lives far south, for example).

Another possible source: KLBJ-AM has three garden shows. You can check out the hosts (Sheryl McLaughlin, John Dromgoole, and Tom Spencer) and find their contact info at http://www.newsradioklbj.com/hosts-Local/index.aspx

None of my favorite nurseries are in Austin but Lowe's and Home Depot have pretty good selections.

Looks like her address is in an area called "South Congress"
This is a rental, so likely shrubs, bedding plants or potted plants are what she'd be buying.

I used to give her gift cards to Logees in CT, but obviously that would only be mail order now!

Two of the best in Austin:

http://www.bartonspringsnursery.net/

http://www.naturalgardeneraustin.com/

Thanks Austin Traveler. I was also told that the Great Outdoors is pretty good. Maybe I'll give her several gift cards!

Yes, Great Outdoors is very good and close to her location. Sorry, forgot about that one!